The piratebay had a list of most popular keywords directly linking to illegal content. Also their very name _pirate_bay made them a target for bad intent. OpenBazaar doesn't link to or has anything in its name offering or encouraging illegal content. I used to work for isohunt by the way who got shut down by the MPAA and it was because of these details that they lost. If OpenBazaar never links to anything illegal and does not host hashes or any other data of anything illegal, then they'll be fine. Another point is that OpenBazaar is at least so far not profiting from anything illegal such as showing ads on pages featuring illegal content, that was a big point against bittorrent search engines.